Effects of losartan and exercise on muscle mass and exercise endurance of old mice.

This study evaluated the effects of angiotensin II type I receptor blocker (ARB) on muscle mass and exercise capacity in healthy older animals. The effects of combined ARB and exercise training were also determined. Eighty 18-month-old mice were randomized into the control group (C), exercise group (E), losartan group (L) and losartan plus exercise group (LE). Mice in the L and LE groups received losartan from drinking water every day. Mice in the E and LE groups trained on a treadmill 30 min per day, 3 days per week for 4 months. Exercise endurance and spontaneous physical activity of mice were measured at baseline and monthly for 4 months. After 4 months of intervention, serum interleukin-6 (IL-6) levels, muscle mass, and muscle fiber cross sectional area (CSA) were measured. Total antioxidant capacity (TAC), lipid peroxidation and IL-6 levels were determined in quadriceps. We found that exercise endurance only increased in the E and LE groups. Muscle TAC levels of E, L, and LE groups were greater than that in the C group. Serum IL-6 and lipid peroxidation levels were not different among groups. LE group, but not E and L groups, had greater muscle mass, larger muscle fiber CSA, and greater muscle IL-6 levels than that in the C group after 4 months of intervention. These results suggest that losartan promotes the adaptions of muscle mass with exercise training in healthy older animals.